Alloy



Patented Dec. 11, 1934 UNITED STATES PATENT OFFICE ALLOY No Drawing. Application November 9, 1933, Serial No. 697,327

2 Claims.

The invention relates to magnesium base alloys containing copper. The invention is particularly concerned with my discovery that additions of the low melting point metals tin and zinc,

5 separately or in combination, effect a marked improvement in magnesium-copper alloys.

A prime object of the invention is the development of magnesium-copper alloys which are susceptible to variations of physical properties by 0 suitable thermal treatments.

I have found that the addition of tin or zinc to magnesium base alloys is especially beneficial in the as cast condition and that the improvement in the properties of the resulting alloys is accentuated by a suitable thermal treatment. For instance, a magnesium base alloy containing about 1.0 per cent of copper and about 6.0 per cent of tin had, in the as cast condition, a tensile strength of 16,600 pounds per square inch and an elongation of 2.8 per cent in 2 inchh. After a thermal. treatment of 20 hours at 450 C. the alloy had a tensile strength of 23,780 pounds per square inch and an elongation of 6.5 per cent in 2 inches. 1

Another magnesium base alloy containing about 4.0 per cent of copper and 3.0 per cent of zinc had, in the as cast condition, a tensile strength of 13,970 pounds per square inch and an elongation of 0.8 per cent in 2 inches. After a heat treatment of 16 hours at about 350 C. it had a tensile strength of about 21,500 pounds per square inch and an elongation of about 3.3 per cent in 2 inches.

' Another magnesium base alloy containing 2.0 per cent of copper, 6.0 per cent of tin, and 2.0 per cent of zinc had, in the cast condition,- a tensile strength of 14,900 pounds per square inch and an elongation of 0.7 per cent in 2 inches: After a thermal treatment of 20 hours at 425 C. it had a tensile strength of 21,486 pounds per square inch and an elongation-of 3.7 per cent in 2 inches.

The tin may be added to magnesium-copper. alloys in amount between about 0.5 .per cent and 20.0 per cent andthe zinc between about 0.5 per alloys of the low melting point metals tin and ,tion of making a preliminary low melting point cent and 6.0 per cent. If used in combination the total amount of tin and zinc should not exceed 20.0 per ,cent. The copper in all cases may be between 0.5 per cent and 15.0 per cent. The heat treatment of magnesium base alloys containing copper with additions of tin and/or zinc should be carried on between about 330 C. and 450 C. I prefer about 425 C. for about 20 hours, although the time may be varied from 1 hour upwards with improved effect over the cast condition. Some alloys I have found especially useful are (1) a magnesium base alloy containing about 2.0 per cent copper and 6.0 per cent tin; (2) a magnesium base alloy containing about 2.0 per cent copper and 4.0 per cent zinc; (3) a magnesium base alloy containing about 2.0 per cent copper, 5.0 per cent tin, and 3.0 per cent zinc. The term magnesium base alloy designates an alloy containing more than 50 per cent of magnesium.

It is particularly fortunate that the improvement in properties hereinabove noted is associated with the addition to magnesium-copper zinc. They alloy readily with magnesium in the 5 proportions claimed hereinbelow and they may be introduced either in the pure state or as alloys of magnesium-zinc or magnesium-tin, 'but because of their relatively low melting point the precau- 

